Habituation to repeated stimulation is a basic property of the nervous system. Eating involves repeated presentation of food cues, and a consistent body of research in humans, non-human primates and rodents has shown habituation to food cues across a wide variety of responses. In the initial funding period we provided the first evidence that non-overweight youth habituate to repeated food cues. The purpose of the proposed studies is to extend this research to determine the relationship between overweight and habituation in children. Research has shown that obese adults habituate to repeated food cues at a slower rate than leaner adults, which maintains food responsiveness and the motivation to eat. If the same is true for overweight youth, slower habituation may contribute to a greater motivation to eat in overweight than non- overweight youth. Specific Aim 1 will compare habituation of motivated responding for food and energy intake for two different foods over repeated trials between non-overweight and overweight 8- 12 year-old children, with the prediction that non-overweight children will habituate to repeated food cues faster than overweight children. One of the hallmark characteristics of habituation is recovery of responding when presented with novel cues. We have observed that non-overweight children recover responding when novel food or non-food stimuli are presented. An important next step is to test whether overweight youth may be more responsive to recovery of eating after presentation of novel food and environmental stimuli. These studies test two different types of dishabituators which children may experience that can influence recovery of eating after habituation. Specific Aim 2 tests the influence of novel foods on recovery of responding after habituation has occurred in overweight and non-overweight youth. We predict that overweight youth will show greater recovery of responding and greater food consumption to novel food than non-overweight youth. Specific Aim 3 tests whether the degree of dishabituation to environmental stimuli will be different for overweight and non- overweight youth. We predict that overweight youth will show greater dishabituation and greater food consumption to environmental stimuli than non-overweight youth. Non-overweight children show slower habituation to food variety than to repeated presentation of the same food, which could explain greater intake when presented with a variety of foods. In Specific Aim 4, individual differences in the pattern of habituation to food variety will be examined by comparing responding for the same food or a variety of high energy density or low energy density foods in non-overweight and overweight children. The prediction is that overweight children will be more responsive to food variety than leaner youth, across both high and low energy density foods. These studies are designed to understand how individual differences in habituation may be an important factor that differentiates overweight and non-overweight youth.